Semiconductor device structures

ABSTRACT

The present invention relates to methods for forming through-wafer interconnects in semiconductor substrates and the resulting structures. In one embodiment, a method for forming a through-wafer interconnect includes providing a substrate having a pad on a surface thereof, depositing a passivation layer over the pad and the surface of the substrate, and forming an aperture through the passivation layer and the pad using a substantially continuous process. An insulative layer is deposited in the aperture followed by a conductive layer and a conductive fill. In another embodiment of the invention, a semiconductor device is formed including a first interconnect structure that extends through a conductive pad and is electrically coupled with the conductive pad while a second interconnect structure is formed through another conductive pad while being electrically isolated therefrom. Semiconductor devices and assemblies produced with the methods are also disclosed.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.13/012,438, filed Jan. 24, 2011, now U.S. Pat. No. 8,268,723, issuedSep. 18, 2012, which is a divisional of U.S. patent application Ser. No.12/395,989, filed Mar. 2, 2009, now U.S. Pat. No. 7,898,064, issued Mar.1, 2011, which is a divisional of U.S. patent application Ser. No.11/219,132, filed Sep. 1, 2005, now U.S. Pat. No. 7,517,798, issued Apr.14, 2009, the disclosure of each of which is hereby incorporated hereinby this reference. This application is also related to U.S. ProvisionalApplication Ser. No. 60/606,355, filed Aug. 31, 2004; U.S. patentapplication Ser. No. 11/138,544, filed May 26, 2005, now U.S. Pat. No.7,109,068, issued Sep. 19, 2006; U.S. patent application Ser. No.11/384,069, filed Mar. 17, 2006, now abandoned; U.S. patent applicationSer. No. 11/198,338, filed Aug. 5, 2005, now U.S. Pat. No. 7,429,529,issued Sep. 30, 2008; and U.S. patent application Ser. No. 12/186,913,filed Aug. 6, 2008, now U.S. Pat. No. 7,880,307, issued Feb. 1, 2011,the disclosure of each of which is hereby incorporated herein by thisreference.

BACKGROUND

1. Field of the Invention

The present invention relates generally to semiconductor manufacturingtechniques and methods of forming electrical contacts in semiconductorsubstrates. More particularly, the present invention relates to methodsof forming through-wafer interconnects in semiconductor substrates andstructures resulting therefrom.

2. State of the Art

Semiconductor substrates often have vias extending therethrough, whereinthe vias are filled with conductive materials to form interconnects(commonly known as a through-wafer interconnect, or “TWI”) used, forexample, to connect circuitry on one surface of the semiconductor deviceto circuitry on another surface thereof, or to accommodate connectionwith external circuitry.

As used herein, a “via” refers to a hole or aperture having conductivematerial or a conductive member therein and which extends substantiallythrough a substrate (e.g., from one surface substantially to anotheropposing surface). The via may be used to accommodate electricalconnection of a semiconductor device, an electrical component, orcircuitry located on a side of the substrate other than where bond padshave been formed. Vias are conventionally formed in a variety ofsubstrates for a variety of uses. For example, interposers for singledie packages, interconnects for multi-die packages, and contact probecards for temporarily connecting semiconductor dice to a test apparatusoften employ vias in their structures.

One known method of forming through-wafer interconnect structuresincludes a process known as spacer etching. Spacer etching is arelatively complicated and costly procedure. Referring to FIGS. 1A-1D aconventional method of forming a through-wafer interconnect using spaceretching is shown. FIG. 1A illustrates a semiconductor device 10 having asubstrate 12 (such as a silicon substrate) with a layer ofborophosphosilicate glass 14 (BPSG) disposed on a surface thereof. Abond pad 16 is formed over the layer of BPSG 14, and a passivation layer18 overlies the bond pad 16. The passivation layer 18 is etched, such asby reactive ion (dry) etching, so as to define an opening in thepassivation layer 18 at a location above the bond pad 16 as shown inFIG. 1B. Another etching process is used to form a hole or an aperture20 that extends into the silicon substrate 12 portion of thesemiconductor device 10 as shown in FIG. 1C.

As also depicted in FIG. 1C, a layer of insulative material 22 (e.g., apulsed deposition layer or “PDL”) is deposited over the passivationlayer 18, the bond pad 16, and an inner surface of the aperture 20.Optionally, a conductive liner may also be coated over the passivationlayer 18, the bond pad 16, and an inner surface of the aperture 20. Byforming the through-wafer interconnect in this manner, the layer ofinsulative material 22 is deposited on the exposed portion of bond pad16 and must be subsequently removed. A spacer etching process may alsobe used to remove portions of the layer of insulative material 22,wherein portions of the layer of insulative material 22 are left on theinner surface of the aperture 20 and on the passivation layer 18 such asis illustrated in FIG. 1D. A conductive filler 24 is disposed in theaperture 20 and placed in contact with the bond pad 16. The filler 24 isexposed through the back surface of the substrate 12 to form theconductive via, as shown in FIG. 1D and as will be appreciated by thoseof ordinary skill in the art.

Under some conditions, e.g., the use of polyimide as a passivationlayer, the PDL film will form cracks on the surface due to a mismatch inthe coefficient of thermal expansion (“CTE”) of the materials. Thesubsequently performed spacer etch will replicate those cracks into thepassivation layer ultimately causing shorting when metal is used to coatthe sidewalls of the via.

It is a continuing desire to improve the manufacturing techniques andprocesses used in semiconductor fabrication including those associatedwith forming TWI structures. It would be advantageous to provide methodsof forming through-wafer interconnect structures having improvedefficiency and which are more cost effective than conventionaltechniques such as those which employ conventional spacer etchingtechniques.

BRIEF SUMMARY

The present invention, in a number of embodiments, includes methods forforming through-wafer interconnects in semiconductor substrates andstructures resulting from the methods. The disclosed methods of formingthrough-wafer interconnects are more efficient, more economical andprovide greater flexibility in the manufacturing and design ofsemiconductor devices in comparison to conventional methods of formingsuch structures.

In accordance with one embodiment of the present invention, a method forforming a through-wafer interconnect in a substrate includes providing asubstrate having a pad on a surface of the substrate and depositing apassivation layer over the pad and the surface of the substrate. Themethod further includes forming an aperture through the passivationlayer, the conductive pad and into the substrate using a substantiallycontinuous process. A dielectric layer is disposed over the passivationlayer and the inner surface of the aperture. The dielectric layer isremoved from the passivation layer while leaving the dielectric layer onthe inner surface of the aperture. The method also includes removing aportion of the passivation layer from the pad to expose a portion of thepad, filling the aperture with a conductive material and contacting theexposed portion of the pad with the conductive material.

In another embodiment, a semiconductor device is described. Thesemiconductor device includes a substrate having a first surface and anopposing, second surface, wherein the first surface has a pad with apassivation layer disposed thereon. An aperture having an inner surfacecoated with a dielectric layer extends through the conductive pad. Thesemiconductor device also includes a conductive layer overlying thedielectric layer, wherein a portion of the conductive layer protrudesfrom the aperture beyond a surface of the conductive pad.

In yet another embodiment of the present invention, a method of forminga semiconductor device includes providing a substrate having a firstsurface and a second, opposing surface and at least two conductive padsdisposed on the first surface. At least two through-wafer interconnect(TWI) structures are formed including a first TWI structure formedthrough the first conductive pad and a second TWI structure formedthrough the second conductive pad. The first TWI structure and the firstconductive pad are electrically connected while the second TWI structureis electrically insulated from the second conductive pad.

In accordance with another aspect of the present invention, anothersemiconductor device is provided. The semiconductor device includes asubstrate having a first surface and a second, opposing surface, a firstconductive pad disposed on the first surface and a second conductive paddisposed on the first surface. The semiconductor device further includesa plurality of through-wafer interconnect (TWI) structures including afirst TWI structure extending through and electrically connected withthe first conductive pad and a second TWI structure extending throughand electrically insulated from the second conductive pad.

In yet a further embodiment, a method for forming a through-waferinterconnect in a substrate includes providing a substrate having a padon a surface of the substrate. The method further includes depositing apassivation layer over the pad and the surface of the substrate, andforming an aperture through the passivation layer and the pad. Adielectric layer is deposited over the passivation layer and an innersurface of the aperture. The method further includes removing a portionof the dielectric layer and a portion of the passivation layer, thusexposing a portion of the pad circumscribing the aperture, filling theaperture with a conductive material, and covering the exposed portion ofthe pad with the conductive material.

Another semiconductor device is disclosed in an additional embodiment.The semiconductor device includes a substrate having a first surface andan opposing, second surface, wherein the first surface has a pad and apassivation layer disposed thereon. An aperture having an inner surfacecoated with a dielectric layer extends through the pad. In thesemiconductor device, an uppermost surface of the dielectric layer isdisposed below a lowermost surface of the pad.

In yet a further embodiment, another method of forming a through-waferinterconnect in a substrate includes providing a substrate having a padon a surface of the substrate and depositing a passivation layer overthe pad and the surface of the substrate. An aperture is formed throughthe passivation layer and the pad. The method also includes depositing adielectric layer over the passivation layer and an inner surface of theaperture, and filling the aperture with a conductive material.

Assemblies of stacked semiconductor devices including through-waferinterconnects, according to the present invention, are also encompassedthereby.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

In the drawings, which depict exemplary embodiments of various featuresof the present invention, and in which various elements are notnecessarily to scale:

FIGS. 1A-1D are cross-sectional views of a substrate illustrating actsof a conventional method of forming a through-wafer interconnect in asemiconductor device as known in the art;

FIG. 2 is a cross-sectional view of a semiconductor device on which oneembodiment of a method of forming a through-wafer interconnect isperformed;

FIG. 3 is a cross-sectional view of the semiconductor device of FIG. 2having an aperture formed therein;

FIG. 4 is a cross-sectional view of the semiconductor device of FIG. 3having an insulative layer and a conductive liner formed in theaperture;

FIG. 5 is a cross-sectional view of the semiconductor device of FIG. 4having a portion of a passivation layer removed to partially expose abond pad;

FIG. 6 is a cross-sectional view of a through-wafer interconnect formedin the semiconductor device of FIG. 5 prior to exposing the interconnectstructure through a backside surface of the substrate;

FIG. 7 is a cross-sectional view of a through-wafer interconnect withthe interconnect structure being exposed through both surfaces of thesemiconductor device;

FIG. 8 depicts a cross-sectional view of a semiconductor device in whicha through-wafer interconnect is formed in accordance with anotherembodiment of the present invention;

FIG. 9 is a cross-sectional view of the semiconductor device of FIG. 8having apertures formed therein;

FIG. 10 is a cross-sectional view of the semiconductor device of FIG. 9having a resist plug, resist layer and mask formed thereon;

FIG. 11 illustrates a cross-sectional view of the semiconductor deviceof FIG. 10 with a portion of a pad exposed;

FIG. 12 is a cross-sectional view of the semiconductor device of FIG. 11after acts of a method of forming the through-wafer interconnects havebeen performed;

FIG. 13 is a cross-sectional view of the semiconductor device of FIG. 12after additional acts of the methods of forming the through-waferinterconnects have been performed;

FIG. 14 is a cross-sectional view of a semiconductor device having twothrough-wafer interconnects formed therein prior to exposing theinterconnect structure through a backside surface of the substrate;

FIG. 15 is a cross-sectional view of a through-wafer interconnect withthe interconnect structure being exposed through both surfaces of thesemiconductor device;

FIG. 16A is a schematic view of one embodiment of a PC board in astacked arrangement with semiconductor devices having through-waferinterconnects produced with the methods of the present invention; and

FIGS. 16B and 16C are enlarged views of various portions of the stackedarrangement shown in FIG. 16A.

DETAILED DESCRIPTION

The present invention, in a number of embodiments, includes methods forforming through-wafer interconnects that extend into a semiconductorsubstrate between a first surface of the semiconductor substrate and asecond surface thereof, and the resulting structures. The presentinvention may be used to form so-called “through-wafer interconnects”(TWIs), which may also be referred to as vias, for electricallyconnecting integrated circuitry of a semiconductor device to integratedcircuitry of another semiconductor device, to other electrical devicesor in higher level packaging. For instance, in one embodiment, the TWIstructures produced using the methods disclosed herein may be formed soas to be electrically connected to a bond pad or other metal structureto allow electrical connection to the integrated circuit and, in anotherembodiment, the TWI structures may be configured to pass through a bondpad without any electrical connection thereto. Semiconductor deviceshaving the TWI structures produced using the methods disclosed hereinmay be used, for example, for stacked die assemblies, chip select pads,and the like.

Referring to FIGS. 2-7, acts in one method of the present invention forforming through-wafer interconnects (TWIs) are disclosed. FIG. 2illustrates a cross-section of an exemplary semiconductor device 100having a first surface 102 and an opposing, second surface 104. Thesemiconductor device 100 includes a semiconductor substrate 106 (e.g., asilicon substrate), a dielectric layer 108 (e.g., borophosphosilicateglass (BPSG)) and a passivation layer 120. A conductive pad or line 122(e.g., aluminum metal) is disposed on the dielectric layer 108. In oneembodiment, the conductive pad 122 may be covered with the passivationlayer 120, for example, after the semiconductor device 100 has beensubjected to one or more tests by contacting the conductive pad 122 ofthe semiconductor device 100 with a test probe, as will be appreciatedby those of ordinary skill in the art.

The substrate 106 may comprise, without limitation, a bulk semiconductorsubstrate (e.g., a full or partial wafer of a semiconductor material,such as silicon, gallium arsenide, indium phosphide, polysilicon, asilicon-on-insulator (SOI) type substrate, such as silicon-on-ceramic(SOC), silicon-on-glass (SOG), or silicon-on-sapphire (SOS), etc.), thatmay include a plurality of semiconductor devices thereof, and,optionally, semiconductor dice. If the substrate 106 is a wafer, thesubstrate 106 may be a full thickness wafer as received from a vendor ora wafer that has been thinned (e.g., thereby defining the second surface104), as by back grinding or wet etching, after fabrication of theintegrated circuitry of the semiconductor device 100).

The passivation layer 120 may comprise a material other than BPSG, forexample, a silicon oxide, silicon nitride, phosphosilicate glass (PSG),borosilicate glass (BSG), or another material, including one of avariety of insulative, organic (polymeric) materials, which areavailable for passivation. The passivation material may be applied bychemical vapor deposition (CVD), plasma-enhanced chemical vapordeposition (PECVD), or other deposition method suitable for the type ofpassivation material used. The dielectric layer 108 may also be framedfrom other dielectric materials such as, by way of example, silicondioxide or silicon nitride. Although not illustrated, it will beappreciated by those of ordinary skill in the art that the semiconductordevice 100 may further include or be further processed to include otherconductive elements, active areas or regions, transistors, capacitors,redistribution lines, or other structures comprising the integratedcircuitry of semiconductor device 100.

The TWIs of the present invention may be formed at the semiconductor dielevel or at the wafer (or other bulk substrate) level, depending on theparticular needs of the manufacturing process. Thus, while FIGS. 2-8illustrate the fabrication of a single TWI in association with a singleconductive pad 122, it should be understood that the semiconductordevice 100 may be constructed to include multiple TWIs and that suchTWIs may be associated with internal circuitry (not shown) or may beformed in “dead space” of the substrate 106 wherein no integratedcircuitry resides.

Referring now to FIG. 3, an aperture 124 is formed as a blind hole inthe semiconductor device 100. In one embodiment, the aperture 124 ispatterned and etched through the passivation layer 120, the conductivepad 122, the dielectric layer 108 (and any other materials that might bedisposed above the substrate 106), and into the substrate 106. Theaperture 124 may be formed by appropriately masking and patterning aphotoresist or other material (e.g., oxide hard mask) and wet or dryetching to form the aperture 124 to a predetermined depth. For example,in one embodiment, the aperture may be formed to a depth ofapproximately 200 μm.

One suitable “wet” metal etch employs a mixture of nitric acid andhydrofluoric (HF) acid in deionized (DI) water. “Dry” etching may alsobe termed reactive ion etching (RIE). Either a wet or a dry etchant maybe used to etch through the passivation layer 120, the conductive pad122 and the dielectric layer 108 to form the aperture 124. In otherembodiments, the aperture 124 may be formed by mechanical drilling, oruse of an electromagnetic device such as a laser for laser ablation ofthe material of substrate 106. After formation, the aperture 124 may besubjected to a cleaning process to remove any unwanted reactants orimpurities formed during the aperture formation process or, in the caseof laser ablation, to remove heat-damaged portions of substrate 106surrounding the aperture 124 and comprising a so-called “heat affectedzone.” One suitable cleaning solvent for such purpose is a 6%tetramethyl ammonium hydroxide (TMAH) in propylene glycol solution.

Referring now to FIG. 4, an insulative layer 126 is deposited on aninner surface of the aperture 124 and over the first surface 102 of thesemiconductor device 100. A conductive layer 128 is subsequentlydisposed on the inner surface of the aperture 124 and the first surface102 of the semiconductor device 100. The insulative layer 126 and theconductive layer 128 may be removed from the first surface 102 bychemical-mechanical polishing (CMP), as shown in FIG. 4, in a mannersuch that the insulative layer 126 and the conductive layer 128 remainon the inner surfaces of the aperture 124. In another embodiment, CMPmay be used to remove the conductive layer 128 from the first surface102 of the semiconductor device 100 while the insulative layer 126 isleft in place on the first surface 102 of the semiconductor device 100(not shown). In yet an additional embodiment, the aperture 124 may befilled with a polymer or a nickel (Ni) plate and solder in order toenable easier and more efficient CMP processing, and protection of theinner surface of the aperture 124 during the CMP process.

The insulative layer 126 may comprise a dielectric material such as, forexample, a pulsed deposition layer (PDL), low silane oxide (LSO),PARYLENE™ polymer such as that which is available from Specialty CoatingSystems division of Cookson Electronics of Providence, R.I., silicondioxide (SiO₂), aluminum oxide (Al₂O₃), an organic polymeric materialsuitable for passivation purposes such as polybenzoxazole (PBO) orbenzocyclobutene (BCB), or combinations of any thereof. Other dielectricmaterials that may be used as the insulative layer 126 includetetraethyl orthosilicate (TEOS), spin-on glass, thermal oxide, a pulsedeposition layer comprising aluminum rich oxide, silicon nitride,silicon oxynitride, a glass (i.e., borophosphosilicate glass (BPSG),phosphosilicate glass, borosilicate glass), or any other suitabledielectric material known in the art. Methods of depositing theinsulative layer 126 are known by those of ordinary skill in the art andmay vary depending on the type of material used for the insulative layer126.

In one embodiment, the conductive layer 128 may include another layersuch as a plating-attractive coating (PAC) or some type of seed layerthat is placed over the insulation layer 126 to enhance the depositionof the conductive layer 128. For instance, titanium nitride (TiN) may beplaced over the insulation layer 126 using chemical vapor deposition(CVD) techniques to act as the PAC for the subsequent deposition of theseed layer with a plating process such as, for example, electroless orelectrolytic plating to form the conductive layer 128.

Other conductive materials that may be used to form the conductive layer128 include, without limitation, titanium (Ti), polysilicon (Si),palladium (Pd), tin (Sn), tantalum (Ta), tungsten (W), cobalt (Co),copper (Cu), silver (Ag), aluminum (Al), iridium (Ir), gold (Au),molybdenum (Mo), platinum (Pt), nickel-phosphorus (NiP),palladium-phosphorus (Pd—P), cobalt-phosphorus (Co—P), acobalt-tungsten-phosphorous (Co—W—P) alloy, other alloys of any of theforegoing metals, a conductive polymer or conductive material entrainedin a polymer (i.e., conductive or conductor-filled epoxy) and mixturesof any thereof.

Other deposition processes that may be used to deposit the variouslayers of the conductive layer 128 include metallo-organic chemicalvapor deposition (MOCVD), physical vapor deposition (PVD),plasma-enhanced chemical vapor deposition (PECVD), vacuum evaporationand sputtering. It will be appreciated by those of ordinary skill in theart that the type and thickness of material of the various layers ormaterials used for the conductive layer 128 and the deposition processesused to deposit the layers of the conductive layer 128 will varydepending on, for example, the electrical requirements and the type ofdesired material used to faun the TWI and the intended use of the TWI.

Referring now to FIG. 5, a portion of the passivation layer 120overlying the conductive pad 122 is removed such as by using aconventional photolithographic patterning and etching process to form anopening over and at least partially expose the conductive pad 122. Forinstance, a mask 129 (FIG. 4) of a photoresist material may be disposed,patterned and developed on the passivation layer 120 and a suitableetchant may be used to remove the portion of the passivation layer 120exposed through an aperture 129 a (FIG. 4) in the mask 129 and form anopening above the conductive pad 122. Further, a portion of theinsulative layer 126 contacting the conductive layer 128 and above theconductive pad 122 may or may not be removed depending on the type ofetchant used. As illustrated in FIG. 5, the portion of the insulativelayer 126 above the conductive pad 122 has been removed to enable easierconnection of the conductive pad 122 to the resulting TWI. In anotherembodiment, the portion of the conductive layer 128 protruding above theconductive pad 122 may be removed such as, for example, with CMP. Inanother embodiment, since the conductive layer 128 may be used toprotect the insulative layer 126 during an etching process, theconductive layer 128 may also be applied over the conductive pad 122 andthe insulative layer 126 after the conductive pad 122 has been exposed(i.e., after the acts described with reference to FIG. 5).

Turning now to FIG. 6, a metal layer 130 is deposited on the conductivepad 122, the inner surface of the aperture 124 (i.e., the inner surfaceof the conductive layer 128), and the external surface of the portion ofthe conductive layer 128 protruding above the conductive pad 122. In oneembodiment, the metal layer 130 may include a nickel and may bedeposited by electroless or electrolytic plating. In another embodiment,the metal layer 130 of nickel may be coated with a further copper layer.In other embodiments, the metal layer 130 may comprise tantalum orcopper, and may be deposited by physical vapor deposition (PVD).

After deposition of the metal layer 130, the remaining portion of theaperture 124 and the defined openings above the conductive pad 122 arefilled with a conductive material 132 such as, for example, solder. Inone embodiment, the solder may be applied with a wave solder process. Inother embodiments, the aperture 124 and the volume above the conductivepad 122 may be filled with other conductive materials 132, which maycomprise a metal, metal powder, a metal or alloy powder, a flowableconductive photopolymer, a thermoplastic conductive resin, resin-coveredparticulate metal material, or other suitable material that may be usedto form a solid, conductive TWI.

As shown in FIG. 7, CMP, conventional back grinding or another knownmechanical or chemical process may be used to complete the TWI structureby exposing the conductive material 132 through the second surface 104of the substrate 106 for subsequent connection to, for example,circuitry of an external component. The resulting TWI structure isconnected to the conductive pad 122 by way of the conductive material132 and the conductive layer 128.

It is noted that, by using the process of the presently describedembodiment, only two etch procedures using a mask are employed; once toform the aperture 124 described with respect to FIG. 3 and then again todefine the opening above the conductive pad 122 as seen in FIG. 5. Theprior art process described herein with reference to FIGS. 1A-1D uses anetching process three different times. For instance, etching is used toopen the bond pad 16, again to form the aperture 20, and spacer etchingis finally used to remove the layer of insulative material 22 aspreviously described herein. Thus, the process of the instant inventionis more efficient than the conventional process of spacer etching asdescribed with respect to FIGS. 1A-1D.

Referring now to FIGS. 8-15, acts associated with a method of formingthrough-wafer interconnects (TWIs) in accordance with another embodimentof the present invention are disclosed. It is noted that various aspectsof the presently described embodiment may be combined with aspects ofother embodiments described herein as will be appreciated by one ofordinary skill in the art. FIG. 8 illustrates a cross-section of anexemplary semiconductor device 140 having a first surface 142 and anopposing, second surface 144. The semiconductor device 140 includes asubstrate 146 (e.g., a silicon substrate), a dielectric layer 148 (e.g.,BPSG), and a passivation layer 150. Two conductive pads 152 a and 152 b(e.g., aluminum metal) are disposed on the dielectric layer 148. In oneembodiment, the conductive pads 152 a and 152 b are covered by thepassivation layer 150 after the semiconductor device 140 has beensubjected to one or more tests by contacting the conductive pads 152 aand 152 b with test probes.

The substrate 146 may comprise, without limitation, a bulk semiconductorsubstrate (e.g., a full or partial wafer of a semiconductor material,such as silicon, gallium arsenide, indium phosphide, polysilicon, asilicon-on-insulator (SOI) type substrate, such as silicon-on-ceramic(SOC), silicon-on-glass (SOG), or silicon-on-sapphire (SOS), etc.) thatmay include a plurality of semiconductor devices thereof, and,optionally, semiconductor dice. If the substrate 146 is a wafer, thesubstrate 146 may also be a full thickness wafer as received from avendor or a wafer that has been thinned (e.g., thereby defining thesecond surface 144) after fabrication of the semiconductor device 140).

The dielectric layer 148 may be formed from materials such as, by way ofexample, silicon dioxide or silicon nitride. Although not illustrated,it will be appreciated by those of ordinary skill in the art that thesemiconductor device 140 may include or be further processed to includeother conductive elements, active areas or regions, transistors,capacitors, redistribution lines, or other structures used to produceintegrated circuitry.

Referring to FIG. 8, it may be desired that, for example, conductive pad152 a is to be ultimately electrically connected to the TWI that is tobe formed in association therewith while conductive pad 152 b is not tobe electrically connected to the TWI that is to be formed in associationwith conductive pad 152 b. For example, in some stacked chipconfigurations, it may be desirable to have a TWI that passes throughone of the stacked chips without electrically connecting to a bond padof the chip. It will further be appreciated that the semiconductordevice 140 may be configured with any number of TWIs, which are eitherelectrically connected to a conductive pad (i.e., as with conductive pad152 a) or not electrically connected to conductive pads (i.e., as withconductive pad 152 b) as well as various combinations thereof.

FIG. 9 illustrates the semiconductor device 140 having apertures 154 aand 154 b formed therein. The apertures 154 a and 154 b may be formed bypatterning and etching through the passivation layer 150, the conductivepads 152 a and 152 b, the dielectric layer 148 (and any other materialsdisposed over the substrate 146), and into the substrate 146. Theapertures 154 a and 154 b may be formed by appropriately masking andpatterning a photoresist or other material (e.g., hard oxide mask) andwet or dry etching to form the apertures 154 a and 154 b to a desireddepth such as, for example, about 200 μm. One suitable “wet” metal etchemploys a mixture of nitric acid and hydrofluoric (HF) acid in deionized(DI) water.

In other embodiments, the apertures 154 a and 154 b may be formed bymechanical drilling, or use of an electromagnetic device such as a laserfor laser ablation. After formation, the apertures 154 a and 154 b mayfurther be subjected to a cleaning process to remove any unwantedreactants, impurities or damaged substrate material resulting from theaperture formation process.

After formation of the apertures 154 a and 154 b, any mask used topattern and etch the apertures 154 a and 154 b is stripped away and adielectric layer 156 is deposited on the inner surfaces of the apertures154 a and 154 b and over the passivation layer 150. The dielectric layer156 may comprise a dielectric material such as, for example, LSO,PARYLENE™, silicon dioxide (SiO₂), aluminum oxide (Al₂O₃), TEOS, orcombinations of any and may be deposited using known techniques.

Referring to FIG. 10, after the dielectric layer 156 is deposited, theapertures 154 a and 154 b are filled with a resist plug 158 such as, forexample, by disposing a polymer resist in the apertures 154 a and 154 band curing the polymer. A mask 159 is then patterned on the structure.In order to form a TWI that is connected to the conductive pad 152 a, anopening (such as, for example, an annular opening as illustrated) isdefined over the conductive pad 152 a to expose the conductive pad 152 asuch as by patterning with the mask 159 and etching with a selectiveetchant that is capable of etching away or removing the dielectric layer156 and the passivation layer 150 overlying the conductive pad 152 asuch as is shown in FIG. 11. The selective etchant exposes a portion ofthe conductive pad 152 a and also removes a portion of the dielectriclayer 156 circumscribing the resist plug 158, such that an uppermostsurface of the dielectric layer 156 disposed in the aperture 154 a isslightly recessed below a lowermost surface of the conductive pad 152 a.

The mask 159 is then stripped away, resulting in the semiconductordevice 140 shown in FIG. 12. Such a process enables a later depositedconductive layer to electrically connect the conductive pad 152 a to aconductive material deposited in the aperture 154 a. In anotherembodiment, the acts of opening the conductive pad 152 a and aperture154 a formation may be reversed in sequence, wherein defining theopening above the conductive pad 152 a occurs first, followed by theformation of the aperture 154 a.

Referring now to FIG. 13, the resist plugs 158 (FIG. 12) are removed byappropriate stripping and a seed layer 160 is deposited over exposedsurfaces of the semiconductor device 140. In one embodiment, the seedlayer 160 is deposited with atomic layer deposition (ALD) techniques toform a layer of tungsten (W) as the seed layer 160. In otherembodiments, the seed layer 160 may comprise tantalum (Ta) or copper(Cu) and be deposited with physical vapor deposition (PVD) techniques,or the seed layer 160 may comprise copper (Cu) or nickel (Ni) and bedeposited with electroplating. In another embodiment, a solder wettablematerial layer 162 may be deposited over the seed layer 160 with anelectroless or electroplating method. The solder wettable material layer162 may comprise nickel (Ni) or other solder-wettable metals.

As shown in FIG. 14, a conductive material 164 such as, for example,solder is deposited over the solder wettable material layer 162 byplating, dipping the semiconductor device 140 in molten solder or otherknown conductive material deposition techniques. The conductive material164 adheres to the majority of the exposed surfaces of the solderwettable material layer 162 and, thus, after deposition of theconductive material 164, an abrasive technique such as CMP or anotherappropriate process may be used to remove the conductive material 164,the solder wettable material layer 162, and the seed layer 160 extendinglaterally between the two TWIs to prevent the various conductivematerials of one TWI to be connected with those of another TWI and,therefore, preventing any shorting therebetween. The CMP process mayfurther be used to remove the dielectric layer 156 and expose thepassivation layer 150 as a flat, controlled surface. In otherembodiments, other conductive materials may be used to fill theapertures 154 a and 154 b to produce a conductive pathway in the TWIs.Other techniques that enable filling of the apertures 154 a and 154 bwith other conductive filler materials, such as a metal or alloy,include physical vapor deposition (PVD), electroplating, or electrolessplating. A solder paste may also be placed in the apertures 154 a and154 b and reflowed. Further, a conductive or conductor-filled epoxy maybe used.

In yet an additional embodiment, an abrasive process such as CMP may beperformed to remove the solder wettable material layer 162 and the seedlayer 160 from the passivation layer 150 before the conductive material164 is deposited. In such an embodiment, a CMP process will again beused to remove any excess conductive material 164 in order to expose thepassivation layer 150 as a flat, controlled surface.

Referring to FIG. 15, TWI structures 166 a and 166 b are completed withthe thinning of the substrate 146, such as by CMP, conventional backgrinding or another appropriate process to expose the conductivematerial 164 through the second surface 144 of the semiconductor device140.

The methods described may be used to form a TWI structure 166 a that isconnected to an adjacent conductive pad 152 a as well as a TWI structure166 b that is not electrically connected to an adjacent conductive pad152 b. The TWI structure 166 b adjacent the conductive pad 152 b that isnot electrically connected to the conductive material 164 goes throughsubstantially the same acts as the TWI structure 166 a having theconductive pad 152 a that is electrically connected to the conductivematerial 164. However, as seen in FIGS. 10-12, an opening is not definedover the conductive pad 152 b. Thus, the insulative layer 156 remainsbetween and electrically isolates the conductive pad 152 b from theconductive layers 160 and 162 and the conductive material 164 asillustrated in FIGS. 13-15.

The semiconductor device 140 may further be configured with aredistribution layer comprising traces and, optionally, associateddiscrete external conductive elements thereon such as solder bumps,which may be formed on either or both of the surfaces 142 or 144 andelectrically interconnected with the TWI structures 166 a and 166 b, aswill be appreciated by those of ordinary skill in the art.

As noted above, after formation of TWI structures 166 a or 166 b, theTWI structures 166 a or 166 b may be exposed on the second surface 144of the semiconductor device 140 using CMP or other known processes inorder to prepare the TWI structures 166 a or 166 b for subsequentconnection to integrated circuitry, if desired. For instance, FIG. 16Aillustrates one embodiment of a higher level packaging system includingTWIs produced with one or more of the methods of the instant invention.For example, a PC board 170, having a first semiconductor device 140 anda second semiconductor device 140′ in a stacked arrangement is depicted.The first semiconductor device 140 may be configured with TWI structures166 a-166 d and the second semiconductor device 140′ may be configuredwith TWI structures 166 e-166 h. Use of such TWI structures 166 a-166 hprovides substantial flexibility in designing and fabricatingsemiconductor devices and related assemblies. For example, referring toFIG. 16B, TWI structure 166 f of the second semiconductor device 140′ iselectrically coupled with TWI structure 166 b of the first semiconductordevice 140 (such as by a conductive bump, solder ball, or otherappropriate structure). TWI structure 166 b is not electrically coupledto the conductive pad (or line) 152 b. Referring to FIG. 16C, theassembly also includes a TWI structure 166 g (of the secondsemiconductor device 140′) that is not connected to an adjacent TWIstructure 166 c (of the first semiconductor device 140). TWI structure166 c is, however, coupled with its associated conductive pad (or line)152 c.

Of course other configurations may be utilized wherein, for example, aTWI structure is connected to an associated bond pad (or line) and anadjacent TWI structure (e.g., the arrangement represented by TWIstructure 166 a, conductive pad 152 a and TWI structure 166 e); orwherein a TWI structure is not coupled to either of an associated bondpad (or line) or an adjacent TWI structure (e.g., the arrangementrepresented by TWI structure 166 d, conductive pad 152 d and TWIstructure 166 h).

Although the foregoing description contains many specifics, these arenot to be construed as limiting the scope of the present invention, butmerely providing certain exemplary embodiments. Similarly, otherembodiments of the invention may be devised that do not depart from thespirit or scope of the present invention. For example, it is noted thatvarious materials, techniques and features discussed with respect to oneembodiment described herein may be utilized in conjunction with anotherembodiment described herein. The scope of the invention is, therefore,indicated and limited only by the appended claims and their legalequivalents, rather than by the foregoing description. All additions,deletions, and modifications to the invention, as disclosed herein,which fall within the meaning and scope of the claims are encompassed bythe present invention.

What is claimed is:
 1. A semiconductor device comprising: a substratehaving a first surface and a second, opposing surface; a firstconductive pad disposed on the first surface; a second conductive paddisposed on the first surface; a plurality of through-wafer interconnect(TWI) structures including a first TWI structure extending through andelectrically connected with the first conductive pad and a second TWIstructure extending through and electrically insulated from the secondconductive pad.
 2. The semiconductor device of claim 1, wherein thesubstrate comprises a semiconductor material selected from the groupconsisting of silicon, gallium arsenide, indium phosphide, polysilicon,silicon-on-ceramic, silicon-on-glass, silicon-on-sapphire, andcombinations of any thereof.
 3. The semiconductor device of claim 1,further comprising a passivation material over the first surface of thesubstrate.
 4. The semiconductor device of claim 3, wherein thepassivation material comprises a material selected from the groupconsisting of silicon oxide, silicon nitride, phosphosilicate glass(PSG), borosilicate glass (BSG), and an organic polymeric material. 5.The semiconductor device of claim 4, further comprising dielectricmaterial between the passivation material and the first surface of thesubstrate and under the first conductive pad and the second conductivepad.
 6. The semiconductor device of claim 5, wherein the dielectricmaterial comprises borophosphosilicate glass, a silicon oxide, orsilicon nitride.
 7. The semiconductor device of claim 1, wherein thefirst TWI structure includes: an insulative material over a surface of afirst aperture between the first surface and the second, opposingsurface; at least one conductive layer over the insulative material overthe surface of the first aperture and at least partially over and inelectrical communication with the first conductive pad; and a conductivematerial filling the first aperture.
 8. The semiconductor device of clam7, wherein the insulative material over the surface of the firstaperture is selected from the group consisting of LSO, a PARYLENE™polymer, silicon dioxide, aluminum oxide, TEOS, polybenzoxazole (PBO),benzocyclobutene (BCB) and combinations of any of the foregoing.
 9. Thesemiconductor device of claim 7, wherein the second TWI structureincludes: insulative material over a surface of a second apertureextending between the first surface and the second, opposing surface; atleast one conductive layer over the insulative material over the surfaceof the second aperture and electrically insulated from the secondconductive pad; and a conductive material filling the second aperture.10. The semiconductor device of clam 9, wherein the insulative materialover the surface of the first aperture is selected from the groupconsisting of LSO, a PARYLENE™ polymer, silicon dioxide, aluminum oxide,TEOS, polybenzoxazole (PBO), benzocyclobutene (BCB) and combinations ofany of the foregoing.
 11. The semiconductor device of claim 9, whereinthe conductive material in the first aperture and the conductivematerial in the second aperture are exposed through the second, opposingsurface in the substrate.
 12. The semiconductor device of claim 11,wherein the at least one conductive layer over the surface of the firstaperture and the at least one conductive layer over the surface of thesecond aperture each comprises a seed layer.
 13. The semiconductordevice of claim 12, wherein the seed layer is selected from the groupconsisting of tungsten (W), tantalum (Ta), copper (Cu), nickel (Ni andtitanium nitride (TiN).
 14. The semiconductor device of claim 12,wherein the at least one conductive layer over the surface of the firstaperture and the at least one conductive layer over the surface of thesecond aperture each further comprises a solder-wettable material layer.15. The semiconductor device of claim 14, wherein the solder-wettablematerial comprises nickel.
 16. The semiconductor device of claim 15,wherein the conductive material filling the first aperture and thesecond aperture comprises a solder.
 17. The semiconductor device ofclaim 9, wherein the conductive material filling the first aperture andthe conductive material filling the second aperture is selected from thegroup consisting of a metal, an alloy other than a solder, a solderalloy, a solder paste, a conductive epoxy and a conductor-filled epoxy.18. The semiconductor device of claim 9, wherein the at least oneconductive layer of the first aperture and the at least one conductivelayer of the second aperture are selected from the group consisting oftitanium (Ti), polysilicon (Si), palladium (Pd), tin (Sn), tantalum(Ta), tungsten (W), cobalt (Co), copper (Cu), silver (Ag), aluminum(Al), iridium (Ir), gold (Au), molybdenum (Mo), platinum (Pt),nickel-phosphorus (NiP), palladium-phosphorus (Pd—P), cobalt-phosphorus(Co—P), a cobalt-tungsten-phosphorous (Co—W—P) alloy, other alloys ofany of the foregoing metals, a conductive polymer or conductive materialentrained in a polymer and mixtures of any thereof.
 19. Thesemiconductor device of claim 11, further comprising discrete externalconductive elements operably coupled to the first TWI structure and thesecond TWI structure on at least one of the first surface and thesecond, opposing surface.
 20. The semiconductor device of claim 19,wherein discrete external conductive elements are operably coupled tothe first TWI structure and the second TWI structure on each of thefirst surface and the second, opposing surface.